Microfiber Based Interferometric Magnetic Field Sensor

Ferrofluid is a new sort of functional nanomaterial with interesting optical characteristics under external magnetic field which receives widespread attention in photonics. Here, we demonstrate a microfiber based interferometric photonic sensor for real-time detection of magnetic field by immersing one beam of microfiber based interferometer into ferrofluid. Since the applied magnetic field can change the refractive index of ferrofluid and the interferometer sensitive to ambient refractive index variation, the interferometric fringe would be shifted under external field. Thus, the magnetic field can be demodulated by monitoring the fringe shift. The proposed sensor was successfully used to detect both static magnetic field range from 0 to 330 Oe and alternating magnetic field with frequency of 50 Hz.